What is a bone marrow biopsy?

In a bone marrow biopsy, a doctor or medical technician removes a small sample of bone marrow from inside bone. The bone is usually taken from the pelvic bone, although occasionally it is taken from the breastbone.

To reach the marrow, a special needle is inserted through the skin and into the bone. The sample is sent to a laboratory and examined under a microscope.

Doctors study the appearance, size and shape of cells in the bone marrow, looking for abnormalities that might indicate disease. They also examine how the cells interact with each other and measure the number of those cells compared to fat and other substances in the sample.

What is bone marrow?

Bone marrow is soft, sponge-like tissue inside the hollow center of larger bones and liquid that looks like blood. Bone marrow produces:

  • Red blood cells, which carry oxygen throughout the body
  • White blood cells, which are part of the immune system that protects the body from foreign invaders and infectious diseases
  • Platelets, which form clots to stop bleeding when blood vessels are damaged

The liquid component of bone marrow contains stem cells, which are maturing blood cells, along with vitamins needed for cell production.

When would a doctor order a bone marrow biopsy?

Doctors might order a bone marrow biopsy if they notice an abnormal number of red or white blood cells or platelets in a blood sample.

  • A low white-blood-cell count might be linked with a viral infection, since white blood cells help fight viruses. Also, a fever of unknown origin or weakened immune system can indicate a shortage of white blood cells.
  • A lack of red blood cells means that a patient has anemia, which can cause tiredness and weakness. The body doesn’t have enough red blood cells to circulate oxygen adequately through the body.

A bone marrow biopsy can help determine if a disease, like cancer, is preventing the bone marrow from creating blood cells. In some cases, doctors can spot changes to blood cells in bone marrow before they can see the changes in blood samples.

Periodic bone marrow biopsies are done in patients already undergoing cancer treatments to see if their bone marrow is working normally again.

What conditions and diseases are diagnosed with a bone marrow biopsy?

Doctors use a bone marrow biopsy to diagnose and help find the cause of:

  • Leukemia, which is cancer of the blood cells. The disease originates in bone marrow and results in too much production of one type of blood cell.
  • Leukopenia or leukocytosis, a condition marked by too many or too few white blood cells.
  • Multiple myeloma, which causes bone damage. Diseased cells are found in the bone or bone marrow.
  • Anemia, a lack of enough red blood cells that carry oxygen throughout the body.
  • Aplastic anemia, a condition that harms the marrow’s ability to produce an adequate number of each blood cell type.
  • Polycythemia, an abnormal increase in blood cell production in the bone marrow.
  • Myelofibrosis, a disorder involving fibrous scar tissue replacing bone marrow. This leads to changes in the shape and number of red blood cells.
  • Thrombocythemia, in which the bone marrow creates too many platelets.
  • Myelodysplastic syndrome, a bone marrow disorder in which stem cells don’t mature properly.
  • Lymphoma, breast cancer or lung cancer, which are diseases that start elsewhere in the body but can spread to bone marrow.

A bone marrow biopsy can also detect abnormalities in chromosomes and vitamin deficiencies, which can trigger the bone marrow to produce red blood cells that are misshaped or too large.

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